If you’re working with electronics, you need an oscilloscope—even if you don’t yet realize it. An oscilloscope allows you to actually see the signals you’re working with and to be more accurate with your electronics, which in turn can help with precision and decision-making.
What Are Oscilloscopes Used For?
The role of the oscilloscope is to capture and display an incoming signal. Sometimes, the signal is recorded, too, so that you can study it in depth later on.
How Do Oscilloscopes Work?
An oscilloscope comes with at least two connectors. One goes to the ground, while the other is used to “probe” a point on a circuit. The difference in voltage between the two points is what’s being captured. Scopes can be analog or digital, but both work in much the same way.
What Features Does an Oscilloscope Need?
Shopping for an oscilloscope means having to wade through jargon, but we’ve got you covered.
Bit Rates and Sample Rates
Most modern scopes are digital and come with built-in ADCs (analog-to-digital converters). The quality of the conversion depends on two factors: the incoming signal sample rate and the number of bits used to describe each sample.
In the world of oscilloscopes,sample rateis expressed in MSPS or GSPS (Mega or GigaSamples Per Second). It’s distinct frombandwidth, which is expressed in Hz. Bandwidth applies to the analog part of the machine—components that collectively act as a low-pass filter, leaving in lower frequencies while excluding higher ones. The “bandwidth” here is the frequency at which the signal is attenuated by a given amount. This is usually 3db, equating to a halving of the signal strength.
Bit depthalso matters. With one bit per sample, we can record two states: on and off or 0 and 1. The more bits we have to play with, the more values we can use to approximate the incoming signal:
A 16-bit oscilloscope can represent 65,536 values, while a 12-bit oscilloscope can only represent 4,096. But bear in mind that, for this digital precision to be meaningful, the signal-to-noise ratio will need to be pretty respectable. We’ve written elsewhereabout binary and why it matters.
Connectors
Oscilloscopes, for the most part, come with eitherBNCorSMA-type connectors. Match your choice with the probes you’re buying. If you’re measuring certain kinds of signal, like line-level audio, you might look for an adaptor that takes TS, TRS, or RCA inputs.
Another consideration is the number of connectors available. Oscilloscopes that offer many inputs can monitor many signals simultaneously. If you’reconnecting devices via I2C or SPI, then this will allow you to overlay the waveforms and check whether everything is falling into sync.
Passive or Active Probe?
Probes can be passive or active. Passive probes come with a built-in resistor and an adjustable capacitor, internally connected in parallel. Active ones are more complex and work via tiny on-board amplifiers. An active probe might be preferable for working with fast signals since they’re less prone to influencing the signal being measured.
Resistance
The value of the probe’s internal resistor determines the amount of impedance you get. The two main options are one megaohm or fifty ohms. If you’re just getting started, then a 1MΩ connection is typically fine. 50Ω probes are typically reserved for low-voltage, high-frequency circuits.
Oscilloscopes Are Great Tools for Electronics Tinkerers
An oscilloscope is a very useful device, whether you’re working in a high-end laboratory or your garden shed. Trying to build and troubleshoot circuits without one is like stir-frying without a wok. Just make the investment, and don’t look back!
